Electronic devices, e.g. computers or mobile communication devices, need input devices in order to allow users to communicate commands or other information to be processed by the computer. Input devices can be designed as pointing devices for communicating a position signal for a cursor to the electronic device. Examples include computer mice, trackballs and joysticks.
Joysticks are increasingly used as pointing devices for mobile communications devices or other hand-held electronic devices. Such joysticks have small dimensions and are usually arranged to be operated by one finger of the user. Most joysticks are two-dimensional, having two axes of movement (similar to a mouse), but three-dimensional joysticks do exist. A joystick is generally configured so that moving the stick left or right signals movement along the X axis, and moving it forward (up) or back (down) signals movement along the Y axis. Further, the stick may be configured so as to be able to be pressed down in order to signal a mouse-click.
An analog joystick is a joystick, which has continuous states, i.e. returns an angle measure of the movement in any direction in the plane or the space, usually utilizing potentiometers, whereas a switch-type joystick gives only on/off signals for four different directions, and mechanically possible combinations (such as up-right, down-left, etc.). In the future, analog joysticks will replace switch-type joysticks for increasingly complicated applications like gaming, navigation, web browsing, etc.
Usually, the movement of the joystick is detected mechanically or magnetically. However, such a configuration involves the risk of premature wear of the components and results in a bulky construction not necessarily being small enough for being integrated into a hand-held device. The power consumption of a joystick of this kind is large and problems exist regarding magnetic radiation and magnetic interference.
A joystick concept based on an optical principle and defining the field of the instant invention has been disclosed in U.S. Pat. No. 6,300,940. This joystick concept overcomes some disadvantages connected with mechanically or magnetically operating joysticks, e.g. high power consumption and the existence of magnetic radiation, but still leaves some problems unsolved. Problems specifically exist regarding the appropriate support structure for allowing the reflecting member to be tilted. The support structures disclosed in U.S. Pat. No. 6,300,940 are made of a flexible rubber material. However, such flexible support structures usually do not meet the high demands in connection with mobile electronic devices, which usually are subject to mechanical shocks, insolation, dust exposure and other external influences, while having to stand several million activations of the joystick. The flexibility and integrity of rubber is negatively affected when getting older and when being exposed to heat and insolation. Further, the support structure as disclosed in U.S. Pat. No. 6,300,940 is not sufficiently protected against dust and other contamination. Moreover, the known support structures cannot be miniaturized to a sufficient extent in order to allow integration into small handheld electronic devices. Further, the known support structures have considerable drawbacks concerning ease of assembly.
Hence, it is an object of the invention, to provide an input device of the type mentioned in the first paragraph and a mobile electronic device of the type mentioned in the first paragraph, which obviates the drawbacks described.